Aerosol transmission of a viable virus affecting swine: explanation of an epizootic of pseudorabies

A Gaussian diffusion model was applied to an epizootic of pseudorabies in ten swine herds located in Decatur County, Indiana, USA to test the hypothesis that the virus can be spread via aerosol. The epizootic occurred during January to March, 1988, spreading through ten farms across an area of about 150 km2. The model included a receptor component that provided an estimate of viruses received by the pig within an enclosed barn. Results show that the diffusion model can explain the spread of the virus during the epizootic for all nine farms to which the virus spread.

Relationship between the indicators of performance and the weight of pneumonic lesions from pigs at slaughter

Lungs from pigs at slaughter were examined and the extent of the lesions was estimated as the percentage by weight of the lung affected by pneumonia in relation to the weight of the whole lung. Linear regression analyses of mean daily gain in liveweight and days to slaughter on the percentage by weight of pneumonic lung were performed. Within a range between 3.32 and 74.55 per cent for the weight of pneumonic lung, a 10 per cent increase in the weight of pneumonic lung was associated with a decrease in mean daily gain of 31.4 g and a 13.2-day increase to slaughter at 104.2 kg liveweight. When subgroups of pigs were evaluated by farm of origin, significant associations between indicators of performance and pneumonia for pigs from only one of the farms were found.

Growth and reproductive performance, during exposure to ammonia, of gilts afflicted with pneumonia and atrophic rhinitis

From 2 to 4.5 months of age, 80 crossbred gilts were reared in a conventional grower unit where they were naturally exposed to mycoplasmal and bacterial pathogens that cause pneumonia and atrophic rhinitis. At 4.5 months of age, gilts were moved to environmentally regulated rooms (4.9 x 7.3 m) and assigned at random to 1 of 2 treatment groups: low aerial concentration of ammonia (4 to 12 ppm; mean, 7 ppm) or moderate aerial concentration of ammonia (26 to 45 ppm, mean, 35 ppm). Low concentration of ammonia was obtained by flushing of manure pits weekly, whereas moderate concentration of ammonia was maintained by adding anhydrous ammonia to manure pits that were not flushed. Gilts were weighed biweekly. Mean daily gain (MDG) was less (P < 0.01) for gilts exposed to moderate concentration of ammonia than for gilts exposed to low concentration of ammonia after 2 weeks in their respective environments. By 4 and 6 weeks, however, MDG was similar between the 2 treatment groups. After 6 weeks in these environments, 20 gilts from each treatment group were slaughtered, and prevalence and severity of lung lesions and snout grades were determined. At slaughter, body weight was greater (P < 0.01) in gilts exposed to low, rather than moderate, ammonia concentration (94.5 vs 86.8 kg; SEM, 3.3 kg). Percentage of lung tissue containing lesions (18 vs 12) and snout grade (2.8 vs 3.1) were similar between gilts exposed to low or moderate concentration of ammonia. The remaining 20 gilts in each treatment group were maintained in their respective environments, exposed daily to mature boars and bred at first estrus.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of galactan on selected microbial populations and pH and volatile fatty acids in the ileum of the weanling pig

Studies were conducted to determine the effect of galactan on the colonization of E. coli and lactobacilli and ileal pH and volatile fatty acid production in the digestive tract of the weanling pig. In each of two replicate trials, eight 21-d-old nursing pigs were cannulated in the terminal ileum. After a 7-d recovery period, the pigs were weaned and randomly assigned to two test diets: 1) a corn-soybean meal-based control diet and 2) a similar diet containing 1% galactan. On d 1 after weaning, all pigs were orally subjected to K88+ E. coli (2 x 10(9) colony forming units). Ileal digesta samples were collected on d 0, 2, 4, 6, 8, and 10 after weaning and assayed for total E. coli, K88+ E. coli, lactobacilli, pH, and VFA. At the end of the trials, the pigs were killed and digesta samples were collected from the stomach, duodenum, cecum, and colon. Assays similar to those performed on the digesta samples collected from ileal cannulas were performed. Pigs fed 1% galactan had lower (P < .10) ileal pH, lower (P < .05) total E. coli on d 6 and 8, and lower (P < .05) K88+ E. coli concentrations in the ileum than pigs fed the control diet. There were no differences in ADG or gain:feed ratio between diets. The VFA concentrations were not different in the ileum between diets. The VFA were higher (P < .10) on d 0 than on any other day of the study. Acetate and isobutyrate concentrations were lower (P < .10) in the cecum in pigs fed 1% galactan.(ABSTRACT TRUNCATED AT 250 WORDS)

Male pseudohermaphroditism of the testicular feminization type in a heifer

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Association between growth indicators and volume of lesions in lungs from pigs at slaughter

Conflicting findings exist among studies on the effect of pneumonia on growth in pigs. We determined the extent of pneumonia in market-weight pigs by use of an objective, volumetric method and linear regression analyses of mean daily gain and days-to-slaughter weight on the percentage of pneumonic lung. In a range of extent of pneumonia between 1.33 and 70.44%, a 10% increase in the volume of pneumonic lung was associated with a decrease in mean daily gain by 41.1 g and a 16.7-day increase in number of days to a slaughter weight of 104.5 kg.

Relationship to growth performance of pneumonia and atrophic rhinitis lesions detected in pigs at slaughter among four seasons

A commercial swine herd was selected for study, because pigs at slaughter repeatedly had lung lesions consistent with enzootic pneumonia and had snout lesions typical of atrophic rhinitis. Pigs born during various seasons of the year were allotted to 4 investigations and were evaluated from birth to slaughter. Individual lungs and snouts were identified and collected at the slaughter plant and later examined for gross lesions of bronchopneumonia and atrophic rhinitis, respectively. Each lesion was scored, and the following comparisons were made within investigations: prevalence and mean scores for lung lesions; prevalence and mean grades for snout lesions; correlations between lung lesion scores and growth indicators; correlations between snout lesion grades and growth indicators; and correlations between lung lesion scores and snout grade scores. Included in the growth indicators were average daily gain during the growing phase, average daily gain during the finishing phase, average daily gain during growing and finishing phases, and days to attain 104.5 kg of body weight. Prevalence of lung or snout lesions, mean values for lung lesion scores, mean values for snout lesion grades, and mean values for the various growth indicators were tested for statistical differences among the 4 investigations. Prevalence of lung lesions was highest (96%) for winter-slaughtered and lowest (81%) for autumn-slaughtered pigs. Mean scores for lung lesions were 7% (summer), 5% (autumn), 9% (winter), and 16% (spring). Prevalence of snout lesions was highest (85%) for spring-slaughtered pigs and lowest (42%) for autumn-slaughtered pigs.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of zearalenone on days 7 to 10 post-mating on blastocyst development and endometrial morphology in sows

First litter sows in naturally occurring post-weaning estrus were hand mated to proven boars and were fed a diet supplemented with zearalenone, an estrogenic mycotoxin (1 mg zearalenone/kg body weight), or a control diet on days 7 through 10 after mating. Embryos (blastocysts) and endometrial biopsies were collected from control and treated sows on days 9, 11, and 13 after mating. All blastocysts harvested on day 9 were spherical; treatment of sows with zearalenone had no effect on blastocyst development. Blastocysts collected from treated sows on day 11 were in stages of elongation comparable to those of blastocysts from control sows but had mild degenerative changes in the embryonic disks, characterized by slightly retarded development and an increase in the number of necrotic cells. Blastocysts collected from treated sows on day 13 were in an advanced stage of degeneration, characterized by circumferential constrictive division, fragmentation, and degeneration and disorganization of the embryonic disk. Feeding zearalenone to pregnant sows had no effect on the normal decrease in height of the endometrial luminal epithelium on days 9 through 13 after mating and no effect on morphologic appearance of secretory vesicles in the endometrial glandular epithelium. The dosage scheme of zearalenone used in this study did not cause any morphologic changes in the endometrium that could be associated with hyperestrogenism.

Evaluation of use of progesterone to counteract zearalenone toxicosis during early pregnancy in gilts

It has been shown that zearalenone disrupts early pregnancy in swine without altering intrauterine content of estradiol 17 beta or progesterone, embryo migration, or estradiol-17 beta synthesis by blastocysts. However, serum concentrations of progesterone were reduced 2 to 3 weeks after mating in gilts that ingested zearalenone. Therefore, progesterone was administered to gilts during early pregnancy to determine whether it could counteract the detrimental actions of zearalenone on embryonic development. Thirty-two crossbred gilts (Hampshire x Chester White x Yorkshire x Duroc) were assigned randomly to a 2 x 2 factorial arrangement of treatments: zearalenone (Z); zearalenone plus progesterone (ZP); progesterone (P); or control (C). From postmating days 4 to 15, Z- and ZP-treated gilts were fed 1 mg of Z/kg of body weight, and P-treated and C gilts were fed ethanol as vehicle in a corn-soybean diet. On postmating days 3 to 15, P- and ZP-treated gilts were injected IM with 100 mg of progesterone, and C and Z-treated gilts were injected with progesterone carrier (15% ethanol, 15% benzyl alcohol, 70% propylene glycol). Blood was collected from gilts by puncture of the jugular vein daily from days 3 to 15, on alternate days from days 17 to 31, and then twice weekly until the end of the experiment. Fetal development was assessed in Z- and ZP-treated gilts on postmating day 47.6 +/- 2.9 by cesarean section and in P-treated and C gilts at slaughter on postmating days 51.2 +/- 3.2. Serum concentrations of progesterone in P-treated gilts were greater on days 7 to 8, 10 to 15, 17, and 19 than in C gilts. Serum concentrations of progesterone were greater on days 8, 10, and 12 in ZP-treated than in C gilts. However, serum concentrations of progesterone were lower in ZP-treated gilts than in C gilts on postmating days 19 to 31.(ABSTRACT TRUNCATED AT 250 WORDS)

Epizootic of pseudorabies among ten swine herds

An epizootic of pseudorabies in 10 swine herds located near Greensburg in Decatur County, Indiana was investigated. Records of Decatur County swine herds previously quarantined because of pseudorabies were obtained. For the 1988 epizootic, clinical findings were considered, location of each of the 10 swine herds in relation to the other herds was determined, and potential fomites were considered. Meteorologic data prior to, during, and after the epizootic were obtained, correlated, and analyzed. A source-receptor model, based on wind direction and speed data, was used to determine whether weather conditions in the Greensburg area enhanced the potential for aerosol spread of pseudorabies virus between herds. On the basis of lack of other modes of spread of pseudorabies and on meteorologic and source-receptor data, aerosol transmission of pseudorabies virus between the 10 herds was probable.

Relationship of growth performance to pneumonia and atrophic rhinitis detected in pigs at slaughter

Three commercial swine herds were selected for study, because pigs at slaughter consistently had lung lesions typical of bronchopneumonia and snout lesions consistent with atrophic rhinitis. Pigs were reared in the conventional system for each herd except that they were identified at birth and weighted at various intervals. At slaughter, individual pig lungs and snout were examined for lesions of pneumonia and atrophic rhinitis, respectively. Lesions were scored and correlated with growth indicators for each pig. Included in the growth indicators were: average daily gain (growing phase), average daily gain (finishing phase), average daily gain (total), and days to reach 104.5-kg body weight. Additionally, for each pig, scores for lung lesions were correlated to grades for snout lesions. Three correlation coefficients for measurements of pigs within herd B were significant and included days to 104.5-kg body weight and grades for snout lesions, -0.15 (P less than 0.02); average daily gain (finishing) and grades for snout lesions, 0.17 (P less than 0.01); and average daily gain (total) and grades for snout lesions, 0.16 (P less than 0.01). Contrary to findings in other investigations, pigs that attained market weight at the youngest age did not have the lowest score for lung lesions, the lowest grade for snout lesions, or the least extensive or severe lesions. Combining data from all 3 herds, the mean scores for lung lesions and mean grades for snout lesions decreased significantly (P less than 0.05) as the age of pigs at slaughter increased. All other statistical correlations were not significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of prepubertal consumption of zearalenone on puberty and subsequent reproduction of gilts

Forty-eight prepubertal gilts (178.7 +/- 4.1 d; 94.2 +/- 4.1 kg), 16 in each of three trials, were assigned randomly to receive 0 (C) or 10 ppm zearalenone (Z) daily in 2.5 kg of a 14% protein finishing ration for 2 wk. Blood samples were collected at 20-min intervals for 4 h 1 wk after the start of the experiment and 1 wk after Z was withdrawn. Two weeks after Z was withdrawn, gilts were exposed to mature boars 15 min per day for 3 wk. Gilts in estrus were mated to two different boars 12 h apart. Twice each week, blood was sampled and analyzed for progesterone to establish age of puberty. Age at puberty differed (P = .008) among replicates but was similar (P = .13) between Z and C gilts within each replicate. Mean serum concentrations of LH were suppressed (P = .025) during consumption of Z (.25 vs .42 ng/ml) but were similar (P = .16) to concentrations in C gilts 1 wk after Z was withdrawn (.35 vs .45 ng/ml). Frequency and amplitude of LH secretory spikes did not differ (P greater than .50) between Z and C gilts during either sampling period. Mean serum concentrations of FSH were similar (P = .25) between Z and C gilts. Number of corpora lutea and live fetuses were similar (P = .29 and P = .94, respectively) between Z and C gilts. Fetal weights were greater (P = .025) and crown to rump length tended to be greater (P = .10) in fetuses from Z gilts.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of zearalenone on days 7 to 10 postmating on intrauterine environment and migration of embryos in sows

On d 7 to 10 postmating, first-litter sows were fed either a control diet or a diet containing zearalenone (ZEN; 1 mg/kg body weight). Surgery was performed on either d 9, 11 or 13 postmating to collect blastocysts and uterine flushings. The rostral and caudal portion of each uterine horn was flushed with phosphate buffered saline, and the blastocysts were separated from the recovered solution. Uterine flushings were analyzed for total Ca, Mg, Zn, estradiol-17 beta (E2 17 beta) and progesterone (P4). Administration of ZEN did not affect the number of blastocysts recovered or the position of embryos within the uterus on d 9 or 11. Blastocysts recovered on d 13 were filamentous and could not be enumerated. Total Ca in uterine flushings of control sows was higher (P less than .001) on d 11 than on d 9 or 13, but intrauterine Ca of ZEN-treated sows did not vary by sampling day (P greater than .05) and was lower (P = .01) than that of controls on d 11. Total intrauterine Mg of ZEN sows was greater (P = .002) than of control sows on d 11 and 13, and total intrauterine Zn of ZEN sows was greater than that in control sows on d 13. There were no differences in total intrauterine P4 or E2 17 beta among ZEN-treated and control sows on d 9, 11 or 13 postmating. Serum concentrations of 13, 14-dihydro-15-ketoprostaglandin F2 alpha (PGFM) increased from d 9 to 13 in control and ZEN-treated sows, but there were no differences between treatment groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Toxicosis in newborn pigs associated with cutaneous application of an aerosol spray containing chlorpyrifos

Weakness, lethargy, ataxia, lateral recumbency, limb paddling, tremors, salivation, and diarrhea were observed in newborn pigs on a commercial swine farm. Many pigs became moribund and died. All had been treated with an aerosol wound spray containing 2.5% chlorpyrifos. A controlled study was undertaken to determine whether the aerosol spray was the cause of these clinical signs. Pigs exposed to aerosol spray containing 2.5% chlorpyrifos at 3 hours (n = 4) and 6 hours (n = 3) after birth developed clinical signs similar to those on the farm; none survived. Pigs exposed at 24 hours (n = 5) after birth developed clinical signs consistent with those that had developed in pigs on the farm; 3 died and 2 survived. Of 3 pigs exposed to the same spray at 36 hours after birth, 1 developed tremors 7.5 hours later and diarrhea 9 hours later, then returned to normal.

Monensin toxicosis in swine: potentiation by tiamulin administration and ameliorative effect of treatment with selenium and/or vitamin E

Modulation of acute monensin toxicosis in swine was evaluated in 2 studies. In study 1, 56 weanling male pigs were allotted to 14 groups of 4 each. Pigs in 7 groups were given tiamulin in the drinking water (to supply 7.7 mg/kg of body weight/day) for 3 days before and for 2 days after monensin administration. Monensin was given as a single oral dose (at 0, 7.5, 15, 25, 50, 75, or 100 mg/kg) to pigs in groups with or without tiamulin exposure. Prominent acute clinical signs of monensin toxicosis (hypermetria, hind limb ataxia, paresis, knuckling of hind limbs, and recumbency) developed by 2 to 6 hours after dosing in pigs given 15 or 25 mg of monensin/kg with tiamulin exposure, but not in pigs given the 15 or 25 mg of monensin/kg without tiamulin exposure. Also, the extent of monensin-induced skeletal muscle damage at 4 days after monensin dosing was enhanced in pigs given 7.5, 15, or 25 mg of monensin/kg and exposed to tiamulin. In study 2, 48 weanling male pigs were allotted to 8 groups of 6 each. Four groups of pigs were given 20 mg of monensin/kg orally, and 4 groups were given 100 mg of monensin/kg orally. For each monensin dose, a group was treated 24 hours before monensin administration with (i) selenium (Se)-vitamin E preparation, 0.25 mg of Se and 68 IU of d-alpha-tocopheryl acetate (vitamin E)/kg, IM; (ii) vitamin E only, 68 IU of d-alpha-tocopheryl acetate/kg; (iii) Se only, 0.25 mg of Se/kg; or (iv) vehicle.(ABSTRACT TRUNCATED AT 250 WORDS)

Age related susceptibility of newborn pigs to the cutaneous application of chlorpyrifos

An aerosol preparation containing 2.5% chlorpyrifos was applied to the tail and umbilicus of newborn pigs. Mortality was 7/7 pigs treated 0-3 hr after birth, 3/5 pigs treated at 24-30 hr, and 0/3 pigs treated 30-36 hr after birth. Clinical signs consistent with organophosphate (OP) toxicosis were demonstrated by pigs that subsequently died or were euthanatized in extremis. Blood and brain cholinesterase (ChE) activities were depressed in affected pigs compared to controls. Only 1/3 pigs treated 30-36 hr after birth had a diagnostically significant depression in blood ChE. These results indicate that piglets one day or less of age are susceptible to OP toxicosis by cutaneous absorption of chlorpyrifos.

Evaluation of criteria for the postmortem diagnosis of mycoplasmal pneumonia of swine

Ten swine from each of five herds believed to be affected with mycoplasmal pneumonia of swine and ten swine from each of five herds believed to be mycoplasmal pneumonia-free were selected for postmortem study. Lungs from the 100 swine were examined; grossly and microscopically for lesions typical of mycoplasmal pneumonia of swine and culturally and by an indirect immunofluorescent procedure for the presence of Mycoplasma hyopneumoniae. Nineteen of the lungs had both gross and microscopic lesions typical of mycoplasmal pneumonia of swine and 13 (68%) of these were infected, i.e. were culturally and/or indirect immunofluorescent positive. Absence of gross lesions did not prove freedom from mycoplasmal pneumonia, 14 of 73 (19%) grossly normal lungs were found to be infected with M. hyopneumoniae. Comparison of the indirect immunofluorescent and cultural examination, as methods of diagnosing mycoplasma pneumonia, revealed that neither procedure alone was reliable in the case of negative results. Ten lungs were indirect immunofluorescent negative and culturally positive and seven were culturally negative and indirect immunofluorescent positive (11 lungs were positive by both procedures). It was concluded that a definitive diagnosis of mycoplasmal pneumonia of swine requires that M. hyopneumoniae be visualized in indirect immunofluorescent stained lung sections or that it be recovered culturally.